Power FET question - RF Cafe Forums

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krc
Post subject: Power FET question Posted: Fri Apr 21, 2006 10:42 pm

Lieutenant

Joined: Fri Apr 21, 2006 10:34 pm
Posts: 3
hi...i am student and this is simple question: i have a power fet that need to be biased at 12 A of current for its Id biasing.however the current source outputs 25 A of current. since i don't have resistor that can handle this level of current what can i do so that only 12 A of current goes in the drain of the current? thanx

kc

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IR
Post subject: Posted: Mon Apr 24, 2006 4:07 pm

Site Admin

Joined: Mon Jun 27, 2005 2:02 pm
Posts: 373
Location: Germany
Hello,

The current passing through the FET's drain is set by the minimal load that you will connect to your circuit. There are many current limiting circuits relatively easy to implement, and you need to use one in your design. Look in Google there are many applications for such circuits.

Here is just a single example from a quick search in Google:

http://www.radio-electronics.com/info/c ... imiter.php

Good luck!

_________________
Best regards,

- IR

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Jeanalmira
Post subject: Posted: Tue Jun 13, 2006 10:21 pm

General

Joined: Tue Mar 15, 2005 11:43 pm
Posts: 65
Location: Singapore
Hi krc :

I agree with IR.
Antoher way to control the drain current, you also may want to limit/set your gate biasing voltage, so that it will give you the desired drain current at respective drain voltage. For doing this, you can try to apply voltage divider in the gate bias line.

I hope it helps.

Cheers,
Jean

Posted 11/12/2012